It is known to diagnose diseases of the breast by visual inspection of mammograms. To display the area of interest, panning and zooming is commonly used. To best assess differences in density, viewing parameters are used to fine-tune the display. For example, window width and window level are used to best use the different shades of gray that are available. One aspect of the analysis of images by the health professional includes the assessment of symmetry of the left and right breast. This may be achieved by display of a pair of breast images, one next to the other. Also, similarity between breast images of the same breast acquired at different moments in time can be assessed in order to arrive at a diagnosis.
The assessment of breast images may include the detection of lesions. The assessment may also include the assessment of the overall shape or appearance of the glandular tissue. This overall shape or appearance may be referred to hereinafter as breast architecture. Architectural distortion is defined in the Breast Imaging Reporting and Data System (BI-RADS) as follows: “The normal architecture (of the breast) is distorted with no definite mass visible. This includes spiculations radiating from a point and focal retraction or distortion at the edge of the parenchyma. Architectural distortion can also be an associated finding.”
In clinical practice, mammograms are often examined in pairs, using the natural symmetry to visually detect abnormalities by detecting asymmetry of glandular tissue of the left and right breast as seen in mammograms. “Breast cancer: the art and science of early detection with mammography: perception, interpretation, histopathologic correlation”, by László Tabár et al., Thieme, 2005, discloses that parenchymal contour change is a sign that may lead to the detection of small invasive tumors without calcification. Screening mammograms tend to be read in batches, with the average time spent for negative cases being about 15 seconds and positive cases about 1 minute, including dictation. The vast majority of screening cases are negative. The task of examining the natural symmetry of mammography image pairs involves a mental effort to compare the shape of the left and right breasts for irregularities. In the field of digital mammography, there is a need for simple and well-designed computer-human interfaces to achieve a clinically acceptable review time.
US 20090220139A1 describes a means for detecting a contour line that surrounds an object area of the mammogram, which is defined by an object.
“Computer-Aided Detection and Diagnosis of Breast Cancer With Mammography: Recent Advances”, IEEE Transactions on Information Technology In Biomedicine, Vol. 13, No. 2, March 2009, pp. 236-251, describes detection of architectural distortion in mammograms. The paper describes using image processing techniques addressing bilateral asymmetry, by applying alignment of the left and right breast images before performing asymmetry analysis. The paper further describes using procedures to compare the corresponding anatomical regions between the left and right breast images in terms of shape, texture, and density. The paper also describes a technique for the detection of bilateral asymmetry that includes a semi-automated texture-based procedure for the segmentation of the glandular tissue and measures of shape and registration cost between views for the detection of asymmetry.